A solicitor has said any statutory inquiry into an alleged smear campaign against Sergeant Maurice McCabe should not be limited to him alone, but should also examine how senior gardaí dealt with a number of whistleblowers.

Trevor Collins is the solicitor for another prominent garda whistleblower, Keith Harrison.

Speaking on RTÉ's This Week, Mr Collins said that if the Government decides to establish a review into the allegations that Sgt McCabe was the victim of an orchestrated smear campaign, then any such inquiry would be incomplete if it did not also include the cases of Garda Harrison and another whistleblower, Garda Nicky Keogh.

His comments follow the completion by Judge Iarfhlaith O'Neill of a review into claims that senior gardaí set out to "bury" Sgt McCabe by spreading damaging and false rumours about him, at a time in 2012 and 2013 when he was making accusations of widespread garda malpractice and misconduct.

The review was established earlier this year after the former head of the garda press office, Superintendent David Taylor, made a protected disclosure to Minister for Justice Frances Fitzgerald in which he claimed he was instructed by senior gardaí to smear Sgt McCabe's reputation by spreading false rumours about his character.

Mr Collins said that the similarities between how Sgt McCabe was allegedly mistreated and how Garda Harrison and Garda Keogh were dealt with bore an "uncanny similarity".

He said it was beyond belief that there was not an orchestrated campaign by some senior gardaí to deliberately target whistleblowers by spreading rumours about them, as well as using other means to discredit and discourage them from their endeavours as whistleblowers.

The review by Judge O'Neill also examined issues relating to an allegation that former garda commissioner Martin Callinan met with Fianna Fáil TD John McGuinness at a time when he was the chairman of the Dáil Public Accounts Committee, and when the PAC had called Sgt McCabe as a witness to discuss the loss of revenue over what Sgt McCabe alleged was the widespread and flagrant abuse of the penalty points system by many gardaí.

This alleged incident was raised in the Dáil under privilege by Mr McGuinness, who said that Mr Callinan made "vile" comments about Sgt McCabe at the meeting.

This prompted the civilian head of Garda Human Resources, John Barrett, to prepare a document on the matter, which was also reviewed by Judge O'Neill.

The judge also reviewed a separate protected disclosure by Sgt McCabe himself, in which he set out issues around the manner in which he was examined by legal counsel for the current Commissioner, Nóirín O'Sullivan, during the O'Higgins Inquiry, which examined other claims St McCabe had made about the management of serious criminal investigations in the Cavan/ Monaghan region.